Stanford University psychologist Philip Zimbardo in 1971 devised a now-classic experiment in which young men were given a daily stipend and assigned to be either prisoners or guards in a role-playing exercise. The "guards" were told not to employ violence, but to keep the "prisoners" under strict control. Although it was a game in a sense, the dynamic that developed was ugly and brings to mind the events at Abu Ghraib.

Zimbardo wrote recently "The terrible things my guards (at Stanford) did to their prisoners were comparable to the horrors inflicted on the Iraqi detainees. My guards repeatedly stripped their prisoners naked, hooded them, chained them, denied them food or bedding privileges, put them into solitary confinement, and made them clean toilet bowls with their bare hands."

The point of the experiment, which was stopped early, was to demonstrate the power of situation-generated forces to shape our behavior. These forces are not irresistible, however, else every prison in the world would be a scene of abuse. Needless to say, authorities should be aware of them and instill discipline in order to counter their effects.

Milgram, Cruelty, and Conformity

Even more chilling is psychologist Stanley Milgram's classic experiment on obedience, in which perfectly ordinary people obey experimenters' demands to deliver what they think are excruciatingly painful electric shocks to other participants. Again the situation seemed to exert a disturbing power over the experiment's participants.

Psychologists have written studies on other more subtle sorts of conformity. In small groups, for example, interactions among members can easily engender extreme actions. If they want to be valued by the group, members freely express opinions in line with what they perceive to be the group's attitudes and suppress those that run counter to those of the group. A prejudicial breeze can soon develop, giving rise to leaders who are much more extreme than the average member.

Links and Nick Berg

In yet another classic experiment also due to Milgram, an experimenter sent a letter to a number of people. It asked each of them to forward the letter to whoever they thought would be most likely to know a specific person and directed the recipients to do likewise until the specific person was reached. Refinements of this experiment have led to an increased understanding of the so-called small world phenomenon — the generally small number of links connecting any two people.

Everyone has heard people exclaim about how amazed they were to run into someone they knew so far from home. (What I find amazing is how they can be continually amazed at this sort of thing.) Most have heard, too, of the alleged six degrees of separation between any two people in this country. Actually, under reasonable assumptions each of us is connected to everyone else by two links, although we're not likely to know who the two intermediate parties are.